1. Field of the Invention
Generally, the invention relates to providing a release mechanism for a picking arm during a picking cycle. More specifically, the invention relates to such a release mechanism having dual pressure yielding means.
2. Description of the Prior Art
Mechanical harvesting of fruit from trees has been attempted using various designs of machines. One class of machines provide for picking members to be inserted and withdrawn from a canopy of the tree. A sub-class of these machines employ picking arms which are displaced generally along there longitudinal length during an extension cycle into the canopy of the tree. It has long been recognized that during such extension into the canopy of the tree that the distal end of a respective picking arm may impact a portion of the tree which produces resistance to continued extension. During such an impaction damage may occur either to the tree, to the machine, or a portion thereof, or to both if continued extension occurs. Various attempts have been made to provide for a release or a yielding of the extension pressure produced by the machine.
These attempts may be identified in three main groups. The first group have resulted in a release within a guiding channel wherein some form of elastic member, generally springs, produce increasing resistance as the picking arm is displaced further from a respective deployed position. This group is not desirable primarily due to a tendency of the picking arm to move violently within the guiding channel to the deployed position when resistance is suddenly eliminated, as exampled by slipping off of an impacted branch. The second group have resulted in a complete release of the respective picking arm from a guide member where little pressure is applied to move the picking arm into the canopy. This group is not desirable primarily due to a tendency to eliminate, or significantly reduce, any opportunity of the picking arm to fulfill the primary function which is to penetrate the canopy and move the picking member(s) into position where engagement of fruit may occur. The third group is limited to machines having a plurality of picking arms. This group provides for all deployed picking arms to operate in a synchronized manner. When the totality of arms meet a predetermined level of resistance, extension of the assembly pauses and withdrawal commences regardless of the extent of the point within the extension portion of the cycle.
Various attempts have been made to provide a devices to provide for a yielding of a picking arm during penetration insertion of a picking arm into a canopy of a fruit tree. These attempts have been less efficient than desired. As such, it may be appreciated that there continues to be a need for a dual pressure yielding assembly which may reset to a deployed position in the event that a resistance level initially exceeds a first level of resistance then falls below the first level of resistance prior to reaching a second level of resistance. The present invention substantially fulfills these needs.